Special belt sander finishing machine



July 3, 1962 D. w. wlLLoTT 3,041,791

SPECIAL BELT SANDER FINISHING MACHINE SSheets-Sheet 1 Filed Sept. 50, 1960 July 3, 1962 D. w. WlLLOTT 3,041,791

SPECIAL BELT SANDER FINISHING MACHINE Filed Sept. 50, 1960 3 Sheets-Sheet 2 M W Whiz 5% 5 BY WM ATTORNEY July 3, 1962 D. w. WILLOTT 3,041,791

SPECIAL BELT SANDER FINISHING MACHINE Filed Sept. 50, 1960 3 Sheets-Sheet 3 A T TOPNEY United States Patent Ofiiice 3,(l4 1,791 Patented July 3, 1962 3,041,791 SPECIAL BELT SANDER FINISHING MACHINE Douglas W. Willott, La Grange, Ill., assignor to General Motors Corporation, Detroit, Micln, a corporation of Delaware Filed Sept. 30, 1960, Ser. No. 59,66 8 Claims. (Cl. 51--147) This invention relates to a polishing or abrading machine, and more particularly to such a machine having a power driven endless abrasive belt for grinding or polishing a workpiece.

An object of this invention is to provide a new improved machine having means for more accurately controlling a polishing or grinding operation. Another object of this invention is to provide a sanding or polishing machine with which the path of movement of an abrading surface can be rigidly controlled relative to a prepositioned workpiece. A further object of this invention is to provide an abrading machine having improved means to control engagement of a power driven abrading surface with a workpiece within a predetermined path of movement of the abrading surface relative to the workpiece. An additional object of this invention is to provide an abrading or polishing machine having manual control mechanism actuable by the machine operator and integrated with power driving mechanism to provide maximum operator selectivity of application of the power driven abrading surface to the workpiece.

Other objects and advantages of the present invention are disclosed in the following detailed description wherein reference is made to the accompanying drawings in which:

FIGURE 1 is a side elevational view of a preferred embodiment of the present invention;

FIGURE 2 is an end view of the apparatus shown in FIGURE 1;

FIGURE 3 is another end view of the apparatus shown in FIGURE 1;

FIGURE 4 is a partial detailed view taken along the line 4-4 in FIGURE 2;

FIGURE 5 is an enlarged detailed view of a portion of the apparatus shown in FIGURE 1; and

FIGURE 6 is a sectional view taken along the line 66 in FIGURE 5.

Referring now to the FIGURES 1 and 2, the machine comprises a base 10 on which a cylindrical workpiece 12 may be supported by any suitable means such as a bracket 114. A movable pedestal 16 is slidably supported on the base 10 between a pair of guide blocks 18, 20. The pedestal 16 is reciprocable Within a guideway formed by the guide blocks 18, 20 and a plurality of bearing members 22, 24 and 26, 28. The pedestal 16 is driven within the guideway by an eccentric drive plate 30 which is connected by a drive shaft 32 to a power source (not shown) through a sprocket wheel 34 or other suitable drive means. The shaft 32 is supported Within spaced trunnions 36, '38, 40' which are secured to the base 10. The eccentric 30 is rotatably mounted within a ring member 42 which is connected to the pedestal 16 through an adjustable coupling 44.

A support plate 46 is secured to the top of the pedestal 16 and supports spaced pillow blocks 48, 50. A tube 52 is rotatably supported within the pillow blocks 48, 50. One end of the tube 52 has a sprocket 54 keyed thereto. A drive sprocket 56 is fixed to a'shaft 58 which is rotatably secured on a bracket 60' fixed to the pedestal 16. A drive chain 62 connects the sprocket wheels 54, 56 and the tube 52 is rotatable by actuation of a hand wheel 64 fixed to the shaft 58.

A support cylinder 66 is fixed tothe other end of the tube 52 and has a radially outwardly extending support flange or arm 68 which terminates in clamping portions 7t), 72. A conventional air motor 74 is secured within the clamping portions 78, 72 with the central axis thereof parallel to the axis of the tube 52. As shown in FIGURE 3, a drive shaft 76 is operatively connected to the motor 74 and has a drive roll 78 secured to the end thereof. A yoke 80' is rotatably secured to the air motor 74 and has a support arm extension 81 on which an idler shaft 82 and idler wheel 84 are rotatably mounted. An abrasive belt 86 is mounted over the drive roll 78 and the idler roll 84, and a surface thereof is supported closely adjacent the periphery of the workpiece 12. In order to counterbalance the weight of the air motor 74 and belt assembly, a counterweight 88 is secured on the end of a radially outwardly extending support bar 90.

The air motor 74 is connected to a suitable high pressure fluid source (not shown) through a flexible conduit 92 and a pipe 94 which is slidably supported within bearings 96, 98 within the tube 52. Referring again to FIGURES 1 and 2, a belt adjustment means is located adjacent the hand wheel 64 to provide for axial adjustment of the supply pipe 94 within the tube 52 for a purpose to be hereinafter described. The belt adjusting means comprises a collar 104 which is fixed to the pipe 94 and a control yoke 102 mounted thereon. The end of the yoke 102 is provided with a threaded bushing portion 104 in which an adjusting screw 106 is threadably engaged. The adjusting screw 106 is rotatably mounted and supported in a bushing 168 secured to a bracket 110 that is fastened to the top plate 46 in any suitable manner. An adjusting knob 112 is provided on the end of the adjusting screw 186 adjacent the hand wheel 64.

Referring now to FIGURES 5 and 6, a belt application pressure control means is shown for controlling the frictional engagement between the abrasive belt 86 and the workpiece 12. A cam housing 114 is slidably mounted on a support plate 116 which is secured to the housing 66 and the support arm 68 in any suitable manner. Sliding motion of the cam housing 114 relative to the plate 116 is permitted by elongated slots 118, 120 and cooperating fastening members 122, 124. A cam block 126 having suitable cam surfaces is fastened to the end of the pipe 94 and is mounted for engagement with similar cam surfaces within a cam slot 128 provided in the cam housing 114 so that axial movement of the pipe 94 causes transverse reciprocable movement of the cam housing 114. A connecting arm 130 extends between the cam housing 114 and a clamp 132 which is fastened to the idler roll support 81 in any suitable manner so that the reciprocable movement of the cam housing 114 causes rotation of the yoke 80 and idler roll support 81 about the air gun 74 to vary the position of the abrasive belt 86 relative to the periphery of the workpiece 12. A backup shoe 134 is held in engagement with the back side of the abrasive belt 86 by a link 136 through a sponge rubber spacer 138%.

In operation, an annular workpiece 12 is mounted adja-cent the endless abrasive belt 86. The central axis of the workpiece is substantially aligned with the central axis of the tube 52 and has an outside radius approximately equal to the distance from the center line of the tube 52 to the adjacent surface of the endless abrasive belt. Although the apparatus shown and described is designed for production polishing of annular workpieces of a particular diameter, it is obvious that the apparatus may be made adjustable to accommodate workpieces of varying diameters by provision of an extensible support arm 68 and connecting link 130. Thus, any suitable adjustable telescopic support arm or link or the like would permit the air gun 74 and abrasive wheel to be variably radially positioned relative to the central axis of the tube 52 to accommodate workpieces having varying diameters. When the workpiece has been positioned adjacent the abrasive belt, the polishing operation is commenced by actuation of the air motor 74 and the eccentric 30 through suitable control mechanism (not shown) adjacent the hand wheel 64 to drive the abrasive belt in an endless path around the drive roll 78 and the idler roll 84. The pedestal 16 is simultaneously reciprocated within the track provided by the guide blocks 18 and 20 to move the abrasive belt back and forth across the workpiece surface to be finished. The control mechanism for actuating the air motor 74 and the eccentric 30 may be placed closely adjacent the hand wheel so that the operator can convenient- 1y actuate all the controls.

In order to finish the appropriate surface area of the workpiece 12, the abrasive belt is manually rotated about that surface by rotation of the tube 52 through the sprockets 54, 56, the chain 62 and the hand wheel 64. At the same time that the abrasive belt is being rotated about the periphery of the workpiece, it is also being reciprocated across the work surface by the reciprocatory action of the pedestal 16 on the base plate 10. In addition to being able to control the circumferential location of the abrasive belt on the periphery of the workpiece, the operator of the machine can control the abrading pressure applied at any given position of the abrasive belt relative to the workpiece by actuation of the knob 112 to linearly shift the air supply pipe 94 within the tube 52. Movement of the air supply pipe 94 forces the cam housing 114 and link 130 to reciprocate transversely of the central axis of the tube 52 by action of the cam 126 in the cam groove 128. The pressure of the abrasive belt against the workpiece is thereby completely controlled by the operator.

Thus, it will be seen that the relationship between a workpiece and a power driven abrading belt may be closely controlled to provide uniform results. The axial reciprocating movement imparted to the belt by reciprocable movement of the pedestal 16 eliminates inherent variations in wearing uniformity of the abrasive belt and grooving of the workpiece surfaces which would result if the motion of the abrasive belt relative to the work surface was continuously unidirectional. The relative movement of the abrasive belt relative to the workpiece is automatically controlled by the apparatus provided and does not require constant manual control and supervision of the operator as in many previous abrading operations. Although the movement between the belt and the workpiece at any particular surface is automatically controlled, the apparatus provides a maximum of manual control for the operator with a minimum amount of physical exertion. Accordingly, the operator can vary the pressure application of the abrasive belt to the workpiece and can vary the position of application of the belt to the workpiece at will. Thus, the belt applying skill of the operator which if often necessary to produce uniform high polished surfaces is retained through manual controls, but tedious manual positioning and holding of the abrasive belt about the periphery of the workpiece is eliminated and does not require the constant attention or manipulative skill of the operator as in previous apparatus.

Obvious changes in the details of construction and the relationship of the parts as disclosed in the preferred embodiment are intended to be included within the scope of the invention as defined by the appended claims.

In the claims:

1. In a polishing machine or the like comprising a base member, track means fixed to said base member, a carriage slidably supported on said track means, drive mechanism fixed to said base member and operably connected to said carriage to cause reciprocation thereof on said track means, spaced bearing means provided on said carriage, shaft means rotatably supported by said bearings, one end of said shaft means extending beyond said carriage, a radially extending support arm fixed to said one end of i said shaft means, an abrading unit adjustably secured to said support arm and being radially spaced from said shaft means, manual means to rotate said shaft means and move said abrading unit in a circumferential path about said shaft means, a fixture for supporting a cylindrical workpiece in coaxial alignment with said shaft means and in abrading engagement with said abrading unit during reciprocable and circumferential movement of said abrading unit, and manual means to vary abrading engagement pressure between said abrading unit and said cylindrical workpiece during said reciprocable and circumferential movement.

2. In an abrading machine for polishing or grinding an annular workpiece; an abrading unit comprising a motor having a drive shaft, a drive roll mounted on said drive shaft, an idler roll support yoke concentrically rotatably mounted relative to said drive shaft and having a. radially extending support arm, an idler roll rotatably mounted on said support arm, an endless abrasive belt mounted on said drive roll and said idler roll for powered movement therearound; abrading unit support means comprising a pedestal member, a control shaft rotatably mounted on said pedestal member, a support bracket fixed to said control shaft and extending radially outwardly therefrom, clamping means provided on said support bracket and adapted to receive and retain said motor at a position radially outwardly spaced from said control shaft; manual control mechanism connected to said control shaft to cause rotation of said control shaft and move said abrading unit in a circumferential path, control linkage connected to said idler roll support yoke to variably position said idler roll relative to said drive shaft of said motor and radially variably position said abrasive belt relative to said control shaft, and workpiece support means to position said annular workpiece circumjacent said circumferential path of said abrading unit whereby said abrasive belt is engageable with the periphery of said workpiece.

3. In a machine of the class described; a workpiece support, a movable pedestal, a trackway, a rotatably mounted support, an endless abrasive belt, a motor, a control rod, belt positioning linkage, a hand Wheel, reciprocable drive mechanism; said pedestal being slidably mounted on said trackway, said reciprocable drive mechanism being connected to said pedestal and operable to reciprocate said pedestal on said trackway, said rotatably mounted support being carried by said pedestal and having a central axis coaxially aligned with a central axis of an annular workpiece adapted to be mounted on said workpiece support, said endless abrasive belt being rotatably driven by said motor and forming an abrading unit therewith, said abrading unit being secured to said rotatably mounted support and movable therewith about the central axis thereof, said abrasive belt being supported in a position adjacent a portion of the outer periphery of the annular workpiece mounted on said workpiece support, said hand wheel being connected to said rotatably mounted support and being actuable to cause rotation of said abrasive unit about the central axis of said rotatably mounted support and about the periphery of said annular workpiece, said belt positioning linkage being connected to said abrasive unit, said control rod being connected to said belt positioning linkage and actuable to variably radially position said abrasive belt relative to said central axis of said rotatably mounted support, and power means to actuate said motor and said reciprocable drive mechanism to simultaneously rotate said abrasive belt and reciprocate said abrading unit relative to said workpiece during rotative movement of said abrading unit by actuation of said hand wheel.

4. In polishing apparatus for use on an annular workpiece, an abrading unit having an abrasive surface adapted to engage said annular workpiece and an air motor drivingly connected to said abrasive surface to cause movement thereof relative to said annular workpiece, pedestal means for supporting said abrading unit, a hollow control shaft mounted on said pedestal means for rotative movement about a central axis, a radially extending support arm fixed to said hollow control shaft, clamping means provided radially outwardly of said central aXis on said support arm to receive and retain said abrading unit, said abrading surface being located radially outwardly from said central axis a distance substantially equal to the radius of said annular workpiece, manual control means fixed to said hollow shaft to cause rotation of said abrading unit in a circumferential path about said central axis, a high pressure air supply pipe concentrically mounted within said hollow control shaft and extending therebeyond, a flexible conduit extending from an end of said air supply pipe adjacent said air motor and being connected to said air motor, a high pressure fluid source connected to said air supply pipe for actuating said air motor and causing continuous movement of said abrading surface relative to said annular workpiece, said air supply pipe being axially slidably mounted Within said control shaft, control linkage extending from said end of said air supply pipe to said abrading unit, adjustment means provided on said abrading unit and being connected to said control linkage to cause radial displacement of said abrading surface relative to said control axis during axial movement of said air supply pipe, pipe control means located adjacent said manual control means to cause axial movement of said air supply pipe and variably position said abrasive surface, and workpiece support means for supporting said annular workpiece in coaxial alignment with said central axis circumjacent said circumferential path so that said abrasive surface may be variably engaged with a portion of said annular workpiece.

5. The apparatus as defined in claim 4 and wherein said pedestal means is movably supported on a track, actuating mechanism connected to said pedestal and being operable to reciprocate said pedestal on said track, and said actuating mechanism being positioned relative to said pedestal to cause a predetermined length of reciprocable movement and cause regulated movement of said abrasive surface axially of said annular workpiece.

6. The apparatus as defined in claim 4 and wherein said manual control means comprises a driven wheel fixed to said hollow shaft, a drive wheel rotatably mounted on said pedestal, an endless drive member connecting said driven Wheel and said drive wheel, and a hand Wheel connected to said drive wheel to circumferentially position said abrading unit relative to said annular workpiece.

7. The apparatus as defined in claim 4 wherein said control linkage comprises a cam housing slidably supported on said pedestal, a cam fixed to said air pipe and engageable with said cam housing to cause sliding transverse movement of said cam housing, and a control link extending from said cam housing and connected to said adjustment means of said abrading unit.

8. The apparatus as defined in claim 7 and wherein said pipe control means comprises a collar fixed to said pipe, a yoke engaged with said collar and extending therefrom, a threaded shaft rotatably supported on said pedestal and threadably engaged with said yoke, said threaded shaft being fixed relative to said pedestal to prevent axial movement thereof, and said yoke being axially movable by rotation of said threaded shaft to cause axial movement of said air supply pipe.

References Cited in the file of this patent 

